1. Field of the Invention
The present invention relates an image taking optical system and an image pickup apparatus equipped with same.
2. Description of the Related Art
With slimming of cellular phones, portable digital assistances, and notebook computers in these years, camera modules with an optical system having an extremely short length along the optical axis are demanded. To meet this demand, many optical systems having a short focal length composed of two or three aspheric lenses have been developed.
In recent years, on the other hand, with technical progress in the field of image pickup elements and an increasing need in the market, small, low-price camera modules having a large number of pixels and a wide angle of view are demanded. Optical systems composed of four lenses having a reduced overall length and improved imaging performance have been developed.
For instance, the image taking lens disclosed in Japanese Patent Application Laid-open No. 2008-268946 and the image taking lens disclosed in Japanese Patent Application Laid-open No. 2008-185880 are composed of four lenses in which correction of chromatic aberration is excellently achieved to enhance the resolving power suitable for use with an image pickup element having an increased number of pixels, though they are small in size.